Seek errors in RAID recovery
Theoretically, data recovery tools are read-only that means that their usage cannot cause any damage. However, in practice, when recovering data you may observe the effect as if the hard disks are being destroyed mechanically.
For example, we took four disks from the NAS, connected them to a PC and launched the RAID recovery tool. Immediately S.M.A.R.T. monitoring software (Cropel) raised alarm because too many seek errors arose. Indeed, these seek errors were caused by the disk vibration that was provoked by the RAID recovery command to move disk heads on all the disks simultaneously. To tell the truth, a NAS device does the same when reading data from an array. However, a regular NAS device is equipped with more vibration-resistant drive mounts and fastenings.
So, when transferring disks from the device managing RAID array to a regular PC, you may get alerts from S.M.A.R.T. monitoring software telling that the values of the Seek Error Rate attribute have changed significantly. Don't worry about the alerts; after a while values of this S.M.A.R.T. attribute will settle at the new level and alarm will stop.